/*
 * Copyright (c) 2004-2022, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors 
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.hisp.dhis.security.acl;

import org.hisp.dhis.common.BaseIdentifiableObject;
import org.springframework.util.Assert;

/**
 * Currently only the two first positions in the access string are used - rw.
 *
 * @author Morten Olav Hansen <mortenoh@gmail.com>
 */
public class AccessStringHelper {
  public enum Permission {
    READ('r', 0),
    WRITE('w', 1),
    DATA_READ('r', 2),
    DATA_WRITE('w', 3);

    private char value;

    private int position;

    Permission(char value, int position) {
      this.value = value;
      this.position = position;
    }

    public char getValue() {
      return value;
    }

    public int getPosition() {
      return position;
    }
  }

  private char[] access = DEFAULT.toCharArray();

  public static final String DEFAULT = "--------";

  // This should be used only when creating a default CategoryOption
  public static final String CATEGORY_OPTION_DEFAULT = "rwrw----";

  // This should be used only when creating a default Category, CategoryCombo
  // and CategoryOptionCombo
  public static final String CATEGORY_NO_DATA_SHARING_DEFAULT = "rw------";

  public static final String READ =
      AccessStringHelper.newInstance().enable(Permission.READ).build();

  public static final String DATA_READ =
      AccessStringHelper.newInstance().enable(Permission.DATA_READ).build();

  public static final String WRITE =
      AccessStringHelper.newInstance().enable(Permission.WRITE).build();

  public static final String DATA_WRITE =
      AccessStringHelper.newInstance().enable(Permission.DATA_WRITE).build();

  public static final String READ_WRITE =
      AccessStringHelper.newInstance().enable(Permission.READ).enable(Permission.WRITE).build();

  public static final String DATA_READ_WRITE =
      AccessStringHelper.newInstance()
          .enable(Permission.DATA_READ)
          .enable(Permission.DATA_WRITE)
          .build();

  public static final String READ_ONLY =
      AccessStringHelper.newInstance().enable(Permission.READ).enable(Permission.DATA_READ).build();

  public static final String FULL =
      AccessStringHelper.newInstance()
          .enable(Permission.READ)
          .enable(Permission.WRITE)
          .enable(Permission.DATA_READ)
          .enable(Permission.DATA_WRITE)
          .build();

  public AccessStringHelper() {}

  public AccessStringHelper(char[] access) {
    this.access = access;
  }

  public AccessStringHelper(String access) {
    this.access = access.toCharArray();
  }

  public static AccessStringHelper newInstance() {
    return new AccessStringHelper();
  }

  public static AccessStringHelper newInstance(char[] access) {
    return new AccessStringHelper(access);
  }

  public AccessStringHelper enable(Permission permission) {
    access[permission.getPosition()] = permission.getValue();

    return this;
  }

  public AccessStringHelper disable(Permission permission) {
    access[permission.getPosition()] = '-';

    return this;
  }

  public String build() {
    return new String(access);
  }

  public String toString() {
    return build();
  }

  public static boolean canRead(String access) {
    return isEnabled(access, Permission.READ);
  }

  public static boolean canDataRead(String access) {
    return isEnabled(access, Permission.DATA_READ);
  }

  public static boolean canWrite(String access) {
    return isEnabled(access, Permission.WRITE);
  }

  public static boolean canDataWrite(String access) {
    return isEnabled(access, Permission.DATA_WRITE);
  }

  public static boolean canReadAndWrite(String access) {
    return isEnabled(access, Permission.READ) && isEnabled(access, Permission.WRITE);
  }

  public static boolean canDataReadAndWrite(String access) {
    return isEnabled(access, Permission.DATA_READ) && isEnabled(access, Permission.DATA_WRITE);
  }

  public static boolean canReadOrWrite(String access) {
    return isEnabled(access, Permission.READ) || isEnabled(access, Permission.WRITE);
  }

  public static boolean canDataReadOrWrite(String access) {
    return isEnabled(access, Permission.DATA_READ) || isEnabled(access, Permission.DATA_WRITE);
  }

  public static boolean isEnabled(String access, Permission permission) {
    return access == null
        || (validateAccessString(access)
            && access.charAt(permission.getPosition()) == permission.getValue());
  }

  public static boolean isValid(String access) {
    return access == null || validateAccessString(access);
  }

  private static boolean validateAccessString(String access) {
    Assert.notNull(access, "access can not be null");

    if (access.length() != 8 || !access.endsWith("----")) {
      return false;
    }

    byte[] bytes = access.getBytes();

    return (bytes[0] == '-' || bytes[0] == 'r')
        && (bytes[1] == '-' || bytes[1] == 'w')
        && (bytes[2] == '-' || bytes[2] == 'r')
        && (bytes[3] == '-' || bytes[3] == 'w');
  }

  public static boolean hasDataSharing(String access) {
    return AccessStringHelper.isEnabled(access, AccessStringHelper.Permission.DATA_READ)
        || AccessStringHelper.isEnabled(access, AccessStringHelper.Permission.DATA_WRITE);
  }

  public static <T extends BaseIdentifiableObject> void copySharing(T source, T target) {
    target.setSharing(source.getSharing().copy());
  }

  public static String disableDataSharing(String access) {
    return access == null
        ? null
        : AccessStringHelper.newInstance(access.toCharArray())
            .disable(Permission.DATA_READ)
            .disable(Permission.DATA_WRITE)
            .toString();
  }
}
